1. Field of the Invention
This invention relates to detergent mixtures containing fatty acid isethionate salts, fatty alcohols and optionally other surface-active ingredients and to liquid personal hygiene preparations of corresponding composition.
2. Description of the Related Art
Fatty acid isethionate salts (FIS) are anionic surfactants which have been known for some time.
By virtue of their high cleaning performance and their favorable skin-cosmetic compatibility, FIS can be used, for example, in bar soaps. A by no means complete overview on the use of fatty acid isethionates in conjunction with other ingredients is given in the following: DE-A 22 36 727. Toilet soap containing 40 to 85% of alkanesulfonates, 3 to 35% of fatty acids and 5 to 30% of fatty acid isethionates or taurides or alkylsulfates. DE-A 24 15 927. Bar soaps containing 30 to 60% of fatty acid isethionates, 2.5 to 25% of soaps and 3 to 25% of electrolyte salts (sodium sulfate, sodium chloride). DE-A 24 61 139. Bar soaps containing 3 to 70% of fatty acid isethionates and 3 to 20% of alkanesulfonates. DE-A 28 13 324. Bar soaps containing fatty acid isethionates and isethionic acid salts and, as processing aids, 2 to 6% of a substituted propanesulfonate. DE-A 29 01 070. Bar soaps containing 20 to 70% of fatty acid isethionates and 5 to 30% of sucrose fatty acid esters. DE-A 29 07 792. Bar soaps containing 20 to 70% of fatty acid isethionates and 30 to 50% of polysorbates. EP-A 0 176 330. Cleaning preparations preferably containing 55 to 98% of soap, 0.5 to 3% of isethionic acid salts and 5 to 45% of fatty acid isethionates. EP-A 0 178 131. A process for the production of bar soaps in which fatty acids and fatty acid isethionates are mixed under certain shear conditions. EP-A 0 189 332. A process for the production of bar soaps in which soap and fatty acid isethionates are mixed in the melt. EP-A 0 249 474. Cleaning preparations containing soap, fatty acid isethionates and antioxidants. EP-A 0 287 300. Cleaning preparations containing 20 to 80% of soap and 10 to 60% of fatty acid isethionates, alkanesulfonates, ethersulfates, alkylbenzenesulfonates, alkylsulfates, olefinsulfonates and/or fatty alcohol ethoxylates. EP-A 0 409 856. Non-foaming bar soaps containing 14 to 38% of fatty acid isethionates, alkylsulfates, alkylsulfonates, monoglyceride sulfates, alkylbenzenesulfonates and/or ethersulfates, 40 to 72% of water-insoluble emulsifiers, 0 to 25% of starch derivatives and 2 to 12% of water. EP-A 0 434 460. A solid detergent composition containing 15 to 35% of soap, 5 to 50% of fatty acid isethionates, 5 to 50% of water and 5 to 50% of organic solvents (methanol, ethanol and/or propanol). EP-A 0 441 652. Bar soaps containing fatty acid isethionates and sulfosuccinates in a ratio by weight of 10:1 to 2:1. EP-A 0 459 769. Cleaning preparations containing at least 25% of soap, 1 to 50% of fatty acid isethionates, 1 to 15% of fatty acids and 1 to 15% of sugar derivatives. EP 0 472 320. Solid skin cleansing preparations containing 20 to 70% of fatty acid isethionates and amphoteric surfactants of betaine structure in a ratio by weight of 10:1 to 2:1. EP-A 0 542 526. Mild cleaning preparations containing fatty acid isethionates, sulfosuccinates and amphoteric surfactants of betaine structure. WO 91/13958. A process for the production of syndet soaps in which an aqueous mixture of 30 to 80% of glycerol ethersulfonates and 5 to 30% of fatty acid isethionates is dried to a water content of 2 to 10% and then molded. WO 93/04161. Syndet soaps containing 40 to 90% of soap, 0.5 to 5% of cationic polymers, 0.5 to 10% of nonionic surfactants with an HLB value of 15 to 19.2 and 0.5 to 10% of fatty acid isethionates. WO 93/06205. Solid personal hygiene preparations containing 4 to 32% of alkylsulfates, fatty acid isethionates, sarcosinates and/or glycerol ethersulfonates, 4 to 30% of paraffin wax and other mild surfactants. WO 93/18130. Personal hygiene preparations in bar form containing 4 to 32% of alkylsulfates, fatty acid isethionates, sarcosinates and/or glycerol ether sulfonates, 4 to 30% of paraffin waxes, other mild surfactants and a mixture of zeolites. Fatty acid isethionates are generally produced and supplied in the form of compounds typically containing from 10 to 30% by weight of free fatty acids. Despite this generally unwanted impurity, products of the type in question have an unfavorably high melting point above 170.degree. C. which seriously restricts their processability.
Now, the problem addressed by the present invention was to reduce the melting point of fatty acid isethionates by the addition of suitable co-surfactants to such an extent that products with an FIS content of at least 70% by weight which could be stirred or flaked at 100.degree. C. would be obtained. Another problem addressed by the present invention was to select the type and quantity of co-surfactants in such a way that the performance properties of the resulting compounds would not be adversely affected. Finally, another problem addressed by the invention was to compound the fatty acid isethionates in such a way that the self-emulsifying systems would be obtained and would lead to stable aqueous emulsions and could also be used as liquid personal hygiene preparations.